Anti-icing combustion air scoop



Mllch 1947' 1.. A. WILLIAMS, JR 2,417,185

ANTI-ICING CONBUSTION AIR SCOOP Filad July 1. 1943 4 Shoots-Shut 1 A42 z/a 20/6 Ja March 11, 9 L. A. WILLIAMS, JR 2,417,135

ANTI-ICING COII BUSTION AIR SCOOP Filed July 1. 1943 4 Sheets-Shoot 2 :h \\.I w: II I IIIIIIIIIIIIIIIIIIAE 'll/ 1 March 11, 1947. L. A. WILLIAMS, JR

ANTLICING COMBUSTION AIR SCOOP Filed July 1. 1943 4 Sheets-Shoot 3 March 11, 1947. 1. A. WILLIAMS, JR 2,417,185

ANTI-ICING COMBUSTION AIR SCOOP Filed July 1, 1943 4 Sheets-Sheet 4 Patented Mar. 11, 1947 UNITED; srA-T as PATENT-OFFICE;

ANTI- ICING COMBUSTION AIR SCOOP Lynn A, Williams, Jr., Northfield, n1., assignor to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Application July 1, 1943, Serial No. 493,040

My invention relates W air scoops particularly designed to form part of the installation of internal combustion heaters on aircraft. 1

It is now common to install internal combustion types of heaters on aircraft to supply heat to the cabin and other spaces in the airto' anti-icing combustion l .6, Claims. (01. 126-410) Fig. 5 is' a transverse section taken on the line 5--5 of Fig. 4; and 1 Fig. 6 is a section through a part of a fourth type of heater installation.v

The installation shown in'Fig. 1 comprises an 3 internal combustion type ofheater. l0 mounted by any suitable means adjacent a wall l2 of the craft where heat is desired. It is usual to supply a combustion air and ventilating air for the heater from a ram or rams so positioned that operation of the aircraft causes theseramstoforce air to the heater. In those installations in which a separate ram is provided for supplying combustion air for the heater, particular; difficulty has been encountered as the result of ice formation and accumulation inthis basin or ram, as such numeral l 6- The heat exchanger l6 has an outer formation and accumulation interferes with and may completely cut off the supply of combustion air to the heater. An object of my invention is to overcome this difllculty.

It isalso desirablejto heat the combustion air for the airplane heater to a very appreciable extent before this air is introduced into the cabin or other part .of an aircraft; The heater ID has a combustion chamber. H which furnishes hot products of combustion to one end of a. heat exchanger indicated generally by reference wall I8 spaced inwardly of the heater casing!!! and an inner sleeve 22 whose ri'ghthand end terminates short of the righthand end of the heat exchanger.

A circumferentially arrangedrow of ventilating air tubes 24 is located between the outer wall l8, and the sleeve 22. The ventilating air tubes 24 are preferablyspaced from each other and i from the wall l6 and sleeve 22 so that hot prodheater in order to facilitate vaporization of the fuel and thorough mixing of the fuel and combustion air to form a highly eflicient combustible mixture.

Another object-of my invention is to provide means for adequately heating this combustion air to produce more complete and eflicient combustion.

Fig. 1 is a sectional view through part of an aircraft heater installation embodying. my invention;

acts of combustion can flow freely 'around and between these ventilating air tubes. The heat exchanger shown is. of the reverse flow type in which the hot products of combustion issuing from the combustion chamber l4 firsttraverse the interior of the sleeve 22 and then turn backwardly around the righthand end of this sleeve to flow backwardly to the outlet opening ,26. provided in the outer wall I8 of the heat exchanger l8.

The heater casing 20 has a tapered inlet end 28 forming part of a ventilating air inlet pipe a of the aircraft structure.

Fig. 2 is a sectional view ,bf a part of marcraft heater installation utilizing a different form of anti-icing combustion air scoop from thatshown in Fig. 1; i

Fig. 3 is a transverse, sectional view taken on the lines 3-3 of Fig. 2;

Fig. 4 is a sectional view through part of a third term of aircraft heater installation;

30 which is supplied with ventilating air ,by a ram 32 projecting outwardly from the wall l2 inlet'end 34 so positioned and directed that operation of the aircraft creates circulation of air through this ram and through the heater casing 20. r

The ventilating air entering the lefthand end of the heater casing 20 absorbs some heat from the walls of the combustion chamberv and additional heat from the heat exchanger IB'. Part.

of the ventilating air passes through the annular passageway 36 formed between the heater casing 20 and the outer wall 18 of the heat exchanger, whereas the remainder of this ventilatine air flows through the ventilating air tubes 24. *The heated ventilating air is discharged from the righthand end ofthe heater into a cabin or other space'to be heated or into a duct system having outlets located in the same or different spaces. It will be understood that the particular form of heat exchanger shown The ram 32 has its combustion chamber and fuel in Fig. 1 has been selected for purposes of illustration only and that other forms of heat exchangers may be used in lieu thereof.

Combustion air for the combustion chamber i4 is supplied by a, ram or combustion air scoop indicated generally by reference character 38. This scoop has a combustion air passage 40 communicating with apipe 42 leading to the combustion chamber i4 and delivering air to the combustion chamber in a direction tangential to the wall of that chamber. In the particular combustion chamber selected for purposes of 11 lustration, fuel is supplied through a nozzle 44 connected by pipe 48 with any suitable source of fuel. A frusto-conical plate 48 is located in the combustion chamber l4 and has openings through which the combustion air passes and which serve to facilitate admixture of this air with the fuel delivered by the nozzle 44. The usual electrical igniter 52 is provided to initiate combustion. The particular arrangement of the mixing means is shown only by way of example and other types of combustion chamber and fuel mixing means may be used in lieu of those shown in this figure.

From Fig.1 it appears as though the combustionair inlet scoop 38 were locateddirectly behind the ram 32 for the ventilating air. The draw ng is diagrammatic, however, in this respect and it is to be understood that the scoop 38 is preferably located out of alignment with the ram 32 or is otherwise so positioned that the ram 32 has no effect on the quantity of combustion air entering the scoop 88. This scoop 38 supplies only combustion air to the heater l0. Since relatively little combustion air is required by this heater, air inlet passage 40 in the scoop 38 has a relatively small diameter and might easily become partially or completely closed by accumulation of ice therein where the airplane is operating under certain atmospheric conditions. Because of the small diameter of the inlet pasthe scoop 38, but I find it desirable to provide additional preheating of this combustion air.

I have accordingly shown the combustion air inlet pipe 42 and the exhaust pipe 58 as having parallel sections which are welded together as indicated at 88 to facilitate the transfer of heat therebetween to further preheat the combustion air. These parallel portions of the pipes 42 and 56 may also be wrapped with insulating material 62 to minimize the escape of heat therefrom. If that portion of the inlet pipe 42 between the insulated wrapping 82 and the combustion chamber I4 is of appreciable length, it may also bedesirable'to wrap this section of the inlet pipe with insulating material.

The anti-icing scoo 38 is preferably formed as a single casting in the form of a housing or hood, although it may be made of several parts welded or otherwise secured together. This scoop is illustrated as being provided with flanges 64, 86 and 88 which are tapped to receive screws 10 for securing the scoop to thewall l2. As shown in Fig. 1, these screws 10 also secure to the wall 12 a plate 12 to which the adjacent ends of the pipes 42 and 56 are welded or otherwise suitably secured. It shouldbenoted that the outer wall 14 of the scoop is streamlined to minimize air resistance and that this streamlining merges with exhaust outlet haust is finally discharged to atmosphere.

The particular design of anti-icing combustion air scoop shown in Fig; lis inexpensive to manufacture, light in weight, easy to install, and offers little resistance to air flow therepast. This particular design is satisfactory for most installations, but for other installations other designs of air scoops may be desirable. In Figs. 2 to 6,

sage 48, any appreciable accumulation of ice therein would seriously interfere with the operation of the heaterand it is extremely important to preventthe accumulation of lcein'this combustion air inlet and an important feature of my invention lies in the means for preventing such accumulation of ice.

The combustion air scoop 88 is especially designed to provide an annular jacket 54 completely surrounding the combustion air inlet 48 and this jacket 54 is connected by a pipe 58 with the heater exhaust outlet 28 whereby all products ofcombustlon leaving the heater flow through the pipe 58 tothe jacket 54. The products of combustion leaving the heater contain sufficient heat to prevent ice formation in the combustion air inlet 40 and thus insure free passage of combustion air through this inlet to the heater it. These exhaust gases are discharged to atmosphere through an exhaust opening 88 formed in the righthand end of the scoop 38. This opening is so positioned relative to the air flow around the sides of thescoop 38 as to provide minimum resistance to forward movement of the aircraft.

While it is of the utmost importance to prevent accumulation of ice in the combustion air inlet,

I it is also desirable to preheat the combustion air sufficiently toaid materially. in the vaporization of the fuel and in the admixture of fuel and air some extent as it flows'through the inlet 48 in inclusive, I have shown other designs of air scoops which may be used in lieu of that shown in Fig. 1. These other designs are particularly adapted for certain installations'and lend themselves especiallyto'particular manufacturing techniques and equipment.

In Figs. 2 and3, I have shown an air scoop indicated generally by reference character 88 and formed of two half sections 82 and 84 welded together, as indicated at 86, 88 and 98, to form a unitary whole. Each half section has a half of the tubular jacket 82 and a half of the air inlet pipe 94. The extreme inlet end of the air inlet'pipe 94 is welded to the adjacent end of the jacket 92, as indicated by reference character 88 in Fig. 3. Immediately back of its extreme forward end, the air inlet is given a curved or Venturi-like shape.

The air scoop 88 is provided with a base 98 which is welded to the inlet pipe 94 and jacket 80, as indicated at I00. This base is tapped to receive screws I02 for. attaching the scoop to the wall I84 of the aircraft. The inlet pipe 94 has a downwardly extendingend I88 which enters the upper end of a pipe I08 leading to the combustion chamber, carburetor, or other fuel mixing means. The jacket 82 has a downwardly extending exhaust inlet H0 adapted to receive the upper end of an exhaust pipe I I2 connected with the exhaust outlet of the heater. The exhaust jacket 92 and adjacent end of the inlet 94 are suitably curved, as best shown in Fig. 2, to offer a minimum resistance to air flow and the righthand end of the Jacket 92 terminates in an exhaust outlet I I4 through which the exhaust gases pass to atmosphere.

In the embodiment of Figs. 2 and 3 the exhaust jacket is somewhat shorter than the air inlet por- 58 through which the heater exto the lower ends of each of these pipes.

- signed to afford somewhat less preheating of the combustion air than is provided in the form of scoop shown in Fig. 1. The several parts of the scoop shown in Figs. 2 and 3 may be made of relatively thin, light weight metal, or of an other suitable metal or material, by stamping or in any other suitable manner; The stamped or otherwise formed parts are then welded to form the completed scoop.

The anti-icing scoop shown ;in Figs-4 and 5 constitutes a unitary structurecomprising an air inlet pipe I20, a two-part exhaust pipe I22, an end plate I24 welded to the lower ends of the inlet and exhaust pipes, a two-piece plate I28 welded to the inlet and exhaust pipes adjacent the Fig. 6 is a modification of that shown in Figs. 4 and 5. In this embodiment of my invention,

the inlet end of'the combustionair pipe I10 is welded as indicated at I12 to the forward. end of the exhaust jacket I14. The other end of. the combustion air pipe I10 is welded or otherwise suitably secured to an end plate I18 containing v openings I18 for passage of exhaust gases therethrough. An exhaust pipe I80 surrounds the major portion of the combustion air pipe I10,

- but has its upper end terminating at some disupper end of .the latter pipe, and an exhaust jacket I28 welded to the inlet end ofthe inlet pipe I20. The entire assembly is illustrated as being secured to the wall I30 of the airplane cabin or other structure by means of nuts and bolts I 32.

The lower end of thescoop assembly is secured I 7 clamped between the plates I24 and I38 and these plates and gasket have suitable openings I44 through which the heater exhaust can pass, as shown in Fig. 4. I

tance from the forward end of the combustion air pipe and exhaust Jacket whereby the exhaust gases pass from the exhaust pipe I80 into the forward end of the exhaust jacket I14.

Both the combustion air pipe and the exhaust pipe are preferably curved, as shown, and this curvature of the exhaust pipe causes the exhaust gases to be discharged from this pipe toward the weld I12, whereby the curved forward ends of the combustion air pipe, and jacket I14 receivea maximum amount of heat. The exhaust pipe I80 is welded, as indicated at I82, to a plate I I84 forming a part ofthe unitary scoop. This scoop is secured to an aircraft wall I88 by means of screws I88 which pass through the plate I84 easily manufactured with conventional equipment and by conventional manufacturing meth- The various elements of the novel scoopshown in Figs. 4 and 5 may be made of any suitable material and may be assembled in the following or any other sui able manner. The lower endof the inlet pipe I20 is inserted in the lower section of the exhaust pipe I22 and plate I24 is secured The upper section of exhaust pipe I22 is then placed upon the lower section of this pipe and the two sections welded together as indicated at I48.

The inlet pipe I20 is then welded to the joint I sections of the exhaust pipe. as indicated at I48. The two sections of plate I28 are next welded to the upper portions of the inlet and exhaust pipes,

of the aircraft mustibe large enough to receive the end plate I24 and after this plate and the lower ends of the inlet and exhaust pipes. have been passed through the wall opening, the scoop is secured to the wall by the nuts and bolts I 32 which pass through the plate I28 and also through over turned edges I54 of the jacket I28.

In the embodiment of Figs. 4 and 5, the combustion air is heated as it passes through that portion of the'inlet pipe I20 which is located in the exhaust jacket I28, so that no ice formation will occur in this pipe and any ice contained in the entering air will be prevented from accumulating in the pipe. Further preheating of the combustion air occurs in that portion of pipes I20 and I28 which are located in exhaust pipes I22 and I40. It should be noted that the exhaust is discharged into the jacket I28 immed ately adjacent the leading edge thereof so that this edge is properly heated to prevent formation or accumulation of ice on this edge. The Jacket I28 is streamlined and terminates in an exhaust outlet I58.

The anti-icing combustion air scoop shown in ,ods. These several scoops may be made of aluminum, stainless. steel, or any other suitable material. It is to be understood that my invention is not limited to the particular details shown and described but may assume numerous other forms and that my invention includes all modifications and variations falling within the scope of the appended claims.

, 'air inlet passage having an opening adapted to face forwardly upon an aircraft and a, space for exhaust gases completely surrounding said air inietpassage substantially to saidopening and open at the rear to the atmosphere, said casting being adapted to project into an air stream created by operation of said aircraft and having a streamlined exterior surface to minimize air' resistance.

'2. An. aircraft heater installation, comprisingan aircraft, a heater on said aircraft and having a combustion chamber and a heat exchanger for receiving hot products of combustion from said said jacket adiacent to said opening, and a flange integral with said means and Jacket, said flange being adapted for attachment to a wall of the aircraft.

3. An aircraft heater installation, comprising an aircraft, a heater on said aircraft and having a combustion chamber and a heat exchanger for -receiving hot products of combustion from said chamber, a scoop device opening to atmosphere toward the front of the aircraft, a Jacket sur- 7 rounding the forward portion of said scoop device to a point immediately adjacent the entrance thereto, said jacket being open to the atmosphere at its rear portion, a pipe connecting said scoop device with the combustion chamber of the heater to deliver air thereto, and a second pipe connecting the forward portion of said jacket with said heat exchanger to deliver exhaust gases to said jacket, said two pipes being in close I proximity to each other for causing a transfer of heat from the exhaust gases in said second pipe to the air in said first named pipe.

4. An air inlet scoop for an aircraft heater, comprising a scoop device having an inlet opening, and a jacket in the form of a housing for mounting the scoop device in operative position on the outer face of a wall portion of an aircraft and closed at its forward end about the scoop device and open at its rear end to the atmosphere so that said jacket encloses said scoop device substantially to the inlet opening, said jacket being provided with an opening at its forward portion for connection of an exhaust pipe to the jacket.

A heater installation of the class described, comprising a heater having a combustion chamber and heat exchanger for receiving hot products of combustion from said chamber, an antiicing scoop adapted to project from the body of a vehicle containing said heater, said scoop comprising an exhaust jacket, said jacket having a closed forward end and an open rear end, an exhaust pipe connecting said heat exchanger with the. forward portion of said exhaust jacket whereby exhaust gases are conveyed to said jacket, a combustion air pipe for conveying corn- 8 6. An anti-icing air scoop, comprising a unitary structure having a fitting for attachment to a wall of an aircraft, said structure providing an air inlet passage having an opening adapted to face forwardly upon an aircraft and a space for exhaust gases completely surrounding said air inlet passage substantially to said opening and open at the rear to the atmosphere, said structure being adapted to project into an air stream created by operation of said aircraft and having a streamlined exterior to minimize air resistance.

LYNN A. WILLIAMS, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 658,169 Avery Sept. 18, 1900 901,075 Darroch Oct. 13, 1908 1,918,568 Schirmir July 18, 1933 1,982,747 Kurth Dec. 4, 1934 171,409 Moyer Dec. 21, 1875 1,965,158 Rogliano July 3, 1934 2,130,385 Fluor, Jr., et a1. Sept. 20, 1938 286,341 Spear Oct. 9, 1883 4,392 Chase Mar. 7, 1846 1,420,142 Pennington June 20, 1922 FOREIGN PATENTS Number Country Date 5,795 British Apr. 28, 1886 719,320 French Nov. 14, 1931 12,056 British -1 1885 217,701 British June 26, 1924 106,292 German Nov. 7, 1899 

